The black-tie crowd at the Race to Erase MS event tomorrow in Los Angeles won’t be graced with the presence of Jason “Gummy Bear” Davis. His mother, Nancy Davis — who is afflicted with the disease and who spearheads the fund-raising gala each year — has shipped Jason off to Utah’s Cirque Lodge drug rehab to make sure he won’t crash the party like he crashed a Golden Globes after-party in January. (His grandmother Barbara Davis publicly scolded him that night, “You shouldn’t be here. Go home!”) Jason, sounding like sour grapes, dissed tomorrow’s event, quipping to a pal: “Given her guest list of Anne Heche, Tom Arnold and other dysfunctional B-listers, I would’ve fit right in.” Maybe his brother Brandon (“Greasy Bear”) will turn up to represent the clan’s younger generation.